In the article it is specifically mentioned that multiple keys are used for the encryption. There is a secret key burned into the A6 processor that is hard to access without the risk of destroying it. This key cannot be destroyed programmatically, so a secondary key on the NAND is destroyed in case of too many attempts. Only that process could be circumvented with this technique, it doesn't address the increasing interval and AFAIK it is not possible to multiply the hacking process without somehow multiplying the A6 chip - i.e. very hard.